Ionic liquid doped organic hole transporting material for efficient and stable perovskite solar cells

• Published in: Physica. B, Condensed matter Condensed matter, 2020-06, Vol.586, p.412124, Article 412124
• Main Authors: Elawad, Mohammed, Lee, Husileng, Yu, Ze, Sun, Licheng
• Format: Article
• Language: English
• Subjects: BuPyIm-TFSI; Cells; Conductivity; Dopants; Electrical properties; Electrical resistivity; Energy conversion efficiency; Hole conductivity; Hole-transporting materials; Ionic liquids; p-Dopant; Perovskite; Perovskite solar cells; Perovskites; Photovoltaic cells; Solar cells; Solar energy; Stability; Sulfonamides; Trifluoromethane; X60
• ISSN: 0921-4526; 1873-2135; 1873-2135
• DOI: 10.1016/j.physb.2020.412124

As a hole transporting material (HTM), N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis (4-methoxyphenyl) spiro [fluorene-9,9′-xanthene]-2,2′,7,7′-tetraamine (X60) in mesoscopic perovskite solar cells (PSCs) has been widely utilized for substitution of the 2,2′,7,7′-tetrakis (N,N-di-p-methoxyphenylamine)-9,9′-spiro-bi-fluorene (spiro-OMeTAD). In this study, we have introduced an ionic liquid N-butyl-N'-(4-pyridylheptyl) imidazolium bis (trifluoromethane) sulfonamide (BuPyIm-TFSI) as a p-dopant to increase the hole conductivity and stability of the X60 based perovskite solar cells. As a result, based on the different concentrations of BuPyIm-TFSI in mesoscopic PSCs, the optimal condition (4.85 mM) showed the best power conversion efficiency (PCE) of 14.65%, which is extremely higher than the device without BuPyIm-TFSI. Moreover, the device based on X60: BuPyIm-TFSI composite HTM at ambient conditions with humidity of ~40% exhibited good PSCs performance with the long-term stability of 840 h. Hence, the use of BuPyIm-TFSI as a p-dopant for X60 played a significant role in enhancing the electrical properties, stability and efficiency of PSCs. •The highest PCE of 14.65% of PSC achieved at a concentration of 4.85 mM of BuPyIm-TFSI.•X60: BuPyIm-TFSI hole transporting material enhanced the stability of PSC devices over 840 h at 40 RH.•Maintain higher than 93% PCE over 840 h at ~40 RH under ambient condition.•The Voc, Jsc, FF, and PCE increase with the increase of concentrations of BuPyIm-TFSI.•New curve of HTM absorbance is observed at 525 nm after doping of X60 with BuPyIm-TFSI, related to the oxidation of X60.